1. Field of the Invention
The present invention relates to a method for driving a discharge display panel, and more particularly, to a method of driving a discharge display panel which performs a gray scale display operation of a unit frame including a plurality of sub-fields with a time-sharing driving scheme.
2. Description of the Background
FIG. 1 shows a structure of a conventional three-electrode surface discharge type plasma display panel (PDP) as an example of a typical discharge display panel. FIG. 2 shows a display cell of the panel shown in FIG. 1. Referring to FIG. 1 and FIG. 2, address electrode lines AR1, AG1, . . . , AGm, and ABm, dielectric layers 11 and 15, Y-electrode lines Y1, . . . , Yn, X-electrode lines X1, . . . , Xn, fluorescent layers 16, barrier ribs 17, and a protective layer 12 are formed between front and rear glass substrates 10 and 13 of a typical surface discharge PDP 1.
The address electrode lines AR1, AG1, . . . , AGm, and ABm are formed in a pattern on the front side of the rear glass substrate 13, and a lower dielectric layer 15 covers them. The barrier ribs 17 are formed on the lower dielectric layer 15 and in parallel with, and in between, the address electrode lines AR1, AG1, . . . , AGm, and ABm. The barrier ribs 17 define display cells and prevent optical crosstalk between the display cells. The fluorescent layers 16 are formed between the barrier walls 17.
The X-electrode lines X1, . . . , Xn and Y-electrode lines Y1, . . . , Yn, which constitute display electrode line pairs, are formed orthogonally to the address electrode lines AR1, AG1, . . . , AGm, and ABm on the rear side of the front glass substrate 10. A display cell corresponds to each intersection of the address electrodes and the X and Y electrode pairs. The X-electrode lines X1, . . . , Xn, and the Y-electrode lines Y1, . . . , Yn may comprise transparent electrode lines Xna and Yna, which are made of a transparent material such as indium-tin-oxide (ITO), and metal electrode lines Xnb and Ynb, which improve conductivity. The front dielectric layer 11 covers the X-electrode lines X1, . . . , Xn and the Y-electrode lines Y1, . . . , Yn. The protective layer 12, which protects the panel 1 from a strong electric field, may be made of an MgO layer, and it covers the front dielectric layer 11. A plasma-creating gas is sealed within a discharge space 14.
In a conventional driving method for the PDP described above, reset, address, and display-sustain operations may be sequentially performed in a unit sub-field. In the reset operation, all display cells are set to a uniform electric charge state. In the addressing operation, a fixed wall voltage is created on the selected display cells. In the display-sustain operation, applying an alternating voltage to all XY-electrode line pairs generates a display-sustain discharge in the selected display cells. The display-sustain operation creates plasma in the discharge space 14, i.e., a gas layer, of the selected display cells, and radiated ultraviolet rays excite the fluorescent layers 16 to emit light.
FIG. 3 shows a typical device for driving the PDP 1 of FIG. 1. The device comprises an image processing unit 66, a control unit 62, an address driving unit 63, an X-driving unit 64, and a Y-driving unit 65. The image processing unit 66 converts external analog image signals into internal digital image signals, such as red (R), green (G), and blue (B) image data, each of which may have 8 bits, a clock signal, and vertical and horizontal synchronous signals. The control unit 62 generates driving control signals SA, SY, and SX according to the internal image signals input from the image processing unit 66. The address driving unit 63 processes the address signal SA to generate a display data signal, and applies the generated display data signal to the address electrode lines. The X-driving unit 64 processes the X-driving control signal SX and applies the processed signal to the X-electrode lines. The Y driving unit 65 processes the Y driving control signal SY and applies the processed signal to the Y-electrode lines.
U.S. Pat. No. 5,541,618 discloses an address-display separation driving method of driving the PDP 1. In this driving method, each sub-field included in a unit frame may comprise separate addressing and display-sustain periods. Accordingly, addressed display cells of an XY-electrode line pair are not sustain discharged until the addressing operation is completed for all display cells of other XY-electrode line pairs. This delay between addressing and sustain discharging may deteriorate the wall charge state of the addressed display cells, thereby reducing the accuracy of the display-sustain discharge.